Conventionally, there is known EGR (Exhaust Gas Recirculation) for recirculating a part of exhaust gas discharged from a cylinder of an engine body of an internal combustion engine to an intake passage. Moreover, there is conventionally known an EGR cooler as a device for cooling the exhaust gas recirculated to the cylinder. The EGR cooler is arranged in an EGR passage for recirculating the part of the exhaust gas discharged from the cylinder to the intake passage, and cools the exhaust gas passing through the EGR passage (hereinafter referred to as EGR gas in some cases) by a coolant. The internal combustion engine includes the EGR cooler, so it is possible to prevent the temperature of the EGR gas from being too high.
Patent Document 1 discloses a heat exchanger including a heat exchange body (which is called honeycomb structure in Patent Document 1) including plural gas passages. When the heat exchanger according to Patent Document 1 is arranged in the EGR passage such that the EGR gas passes through the heat exchange body according to Patent Document 1, the heat exchanger according to Patent Document 1 exerts the function as the EGR cooler. Also, Patent Document 1 discloses a material including SiC used as the material of the heat exchanger.
In caparison with a metal such as a stainless steel, SiC has a good thermal conductivity and a good corrosion resistance to the exhaust gas. When the heat exchanger including the heat exchange body made of the material including SiC according to Patent Document 1 is used as the EGR cooler, it can be considered to improve the cooling performance and the corrosion resistance of the EGR cooler.